1. Field of the Invention
The invention relates to an article of furniture, more particularly to a table, with a table top height continuously adjustable in a stepless fashion to the particular body dimensions of the user.
While the invention has particular application for supporting computer consoles or terminals of data processing systems and will be described hereinafter for such use, it is to be understood that the present invention may be utilized as a table to support or hold other articles.
2. Description of the Prior Art
The construction of computer consoles used to support a computer terminal such as a typewriter-like device or a cathode ray tube having a data entry keyboard as used in offices, factories or the like, is based on the recognition that the best possible efficiency of a worker is only achieved if the operator can suitably assume a comfortable and anatomically correct seated or standing position at his work place. In a data processing environment, this means placing the keyboard at a comfortable height for data entry by the operator's hands as well as a comfortable height so that data can be easily read from an associated data display on the terminal. Also such correct working position contributes considerably to remaining in health. In order to be able to adapt the computer console to the body dimensions of the user, it is necessary to construct a table such that the table top adjustable in height in the vertical direction.
One method of adjusting the heights of a table is disclosed in U.S. Pat. No. 3,595,180 entitled "Adjustable Heights Device for Data Processing Equipment" issued to Vincent H. Swoyer which describes the placement of tubular extensions having a cross-section the same as each of the four supporting legs. As described in this patent, the extensions support the equipment at a height from which it can be operated easily by a person standing at the table, and when the extensions are removed by sliding them off all ends of the table legs, the table is then supported at its lower level from which it may be conveniently operated from a person at a seating position. Although this patent describes a method for adjusting the heights of a table which is intended for adjusting the heights of the word processing equipment or a table from that of a seating position to a standing position or vice versa, this same method could equally well be employed for adjusting the height to various seating positions or standing positions by providing a variety of extension supports of varying lengths such that the height of the table could be adjusted to the individual operator. However, this method has the great disadvantage that placement and removal of the extension supports requires that the total weight of the equipment be lifted from the floor while the extension supports are put in place or removed. It is therefore not practical to be employed to adjust the equipment to the most efficient heights for individual operators on a hourly or daily basis to compensate for the variety of individuals operating the equipment. Therefore, what is needed is a method by which the table height of data processing equipment may be rapidly and easily adjusted.
It is known to use the so-called gas spring in various pedestal-supported tables as a means of continuously adjusting the height of the table top in a stepless fashion. The gas spring is a pneumatic spring in which the compressing power and extension power is determined by: the gas-filling pressure, the piston rod surface, the friction and the ratio of the filling volume to gas volume with the piston rod in the compressed position. Among the various U.S. patents which disclose the use of a gas spring as a means for adjusting the height of a chair seat or table top are U.S. Pat. No. 3,711,054 entitled "Continuously Adjustable Lifting Devices" issued to Fritz Bauer, U.S. Pat. No. 3,825,244 entitled "Hydraulically Lockable Lifting Device" issued to Fritz Bauer, U.S. Pat. No. 3,837,704 entitled "Seating Furniture" issued to Fritz Bauer, and U.S. Pat. No. 4,108,416 entitled "Device for Adjusting Length of Gas Spring" issued to Toshiro Nagase and Sagamihara Susumu Hatakeyama. All of these U.S. patents disclose using a gas spring in a telescoping pedestal column which is extended or shortened to raise or lower the seat or table top. Tables constructed to use with pedestal columns appear to have problems in providing for the jam-free extension or shortening of the pedestal column as the height of the table is adjusted. This appears to be a particular problem when the load on the table is placed off-center to the pedestal column. Further, the off-center placement of a load on a table supported by a single pedestal column requires that the pedestal have a large foot section so that the table has lateral stability and will not tip over. In addition, if heavy loads are to be placed on a table, the table top surface itself may have to be braced along its perimeter and braced to the pedestal column top so that the table top will not be twisted or excessively flexed by large loads. Also, the placement of a pedestal column with a large cross-section in the center of the table may interfere with the legs of the operator seated at the table and prohibit the operator from assuming a comfortable position.
A computer console constructed in this manner is understandably expensive to manufacture since the possibility of table height adjustment necessarily adds structure and parts not found in computer consoles with fixed heights tables. If the table heights is readily adjustable by means of a one or more operating levers, it is usually necessary to distribute and arrange the operating levers in places on the table frame carrying the table top surface, most of these places being inaccessible by the user while in the operating position, be it seated or standing. Consequently, frequently the greatest part of the adjustment possibility is not explored at all. Apart from this, a large number of operating levers detracts from the shape and appearance of the computer console so that in spite of the existing requirement, the table heights in most computer consoles is at a fixed height in order to simplify and accordingly make more economical the manufacture of such computer consoles.
In U.S. Pat. No. 3,444,830 entitled "Adjustable Gas Spring Supported Drawing Table" issued to Hans Peter Doetsch describes a drawing table supported by a gas spring in which the raising and lowering of the drawing table can be accomplished by means of a single lever. For such height adjustments, the drawing board is provided near each vertically extended side thereof with a pair of arms which are pivotably connected to the drawing board and to the frame and together with the frame of the drawing board form a parallelogram. For locking the drawing board in a fixed position at any level to which it is adjusted, a locking means is provided at one of the pivot points, for example at the pivot point between the upper arm and the frame. To compensate for the weight of the drawing board at any level thereof, one end of gas spring is typically connected to the upper arm at a suitable distance from the pivot of the arm in the frame while the other end of the gas spring is typically connected to the base of the frame so that the entire gas spring extends in a substantially vertical direction. This drawing table offers numerous advantages over older known designs, but is still relatively complicated in its design; in particular, the construction of the arms with the pivots at the end thereof is relatively costly to manufacture. Further, the service of the drawing table extends primarily in the vertical plane and does not present a horizontal surface on which a computer terminal may be rested and would therefore require yet additional structure in order to provide a horizontal surface whose height is adjustable in the vertical direction.